A liquid crystal display device of IPS mode is constituted such that a pair of transparent substrates are arranged to face each other in an opposed manner with a liquid crystal layer being disposed therebetween, and pixel electrodes and counter electrodes, which generate an electric field (lateral electric field) parallel to the transparent substrate between the counter electrode and the pixel electrode, are formed on each pixel region on a liquid-crystal side of one of such transparent substrates. Such a liquid crystal display device is a known display device having broad viewing angle characteristics, whose display is not changed even when viewed from a direction oblique to a display surface. Heretofore, in the liquid crystal display device IPS mode, the counter electrodes are formed on the whole pixel region, except for the periphery of the pixel region.
Recently, a tablet-type information terminal and a multifunctional mobile phone (so-called smartphone) including a touch screen have become popular. There has been proposed a touch screen in which the image display device and the contact-detection type input device are not separately formed but integrally formed. Such a touch screen is referred to as, for example, “embedded type” or “in-cell type”. In this case, a plurality of common electrodes for display are segmented into a plurality of touch driving regions and touch detecting (sensing) regions, thereby allowing a mutual capacitance to be generated between the touch driving region and the touch detecting region. Therefore, the display device measures the change of a mutual capacitance that occurs due to a touch, and thus determines whether a touch has occurred.
When various functions are added to the liquid crystal display device of IPS-mode, it is necessary to apply not only a common electric potential for a display but also a plurality of types of other kinds of signals to the common electrodes formed in the same layer at the same time. In this case, it is necessary to detour around wirings so that common electrodes to which different signals are applied do not short-circuit each other. For example, in the case of a liquid crystal display with a touch panel system inside, common electrodes are divided into plural touch regions. Each touch region performs a function of a touch driving electrode or a touch detecting electrode. Then it may be necessary to connect common electrodes having the same function with each other and to prevent two kinds of common electrodes with different functions from short-circuiting each other. This leads to complicated wirings, a decrease in a pixel aperture ratio and an increase in the steps of a manufacturing process.
Hence, one or more embodiments of the present application have an object to provide a liquid crystal display device of IPS-mode manufactured by a simple manufacturing process with an enhanced pixel aperture ratio.